(a) The electric cooperative tax shall be computed as follows: (1) one-fourth mill per kilowatt hour for cooperatives that have furnished electric energy and power to consumers for less than five years as of December 31 of the preceding calendar year;
(2) one-half mill per kilowatt hour for cooperatives that have furnished electric energy and power to consumers for five years or longer as of December 31 of the preceding calendar year.
(b) In this section, “mill” means one-tenth of one cent.